Invasions within South Africa’s Marine Protected Areas network

Invasions within South Africa’s Marine Protected Areas network
Tamara B. ROBINSON1, Ben Brooker2, Coleen L Moloney2
1Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Matieland, 7602
2Department of Biological Sciences, University of Cape Town, Rondebosch 7701

Despite an increasing research focus on marine invasions along the South African coastline, the presence of alien species has previously only been considered in three marine protected areas (MPAs). To address this gap in current knowledge this study surveyed nineteen of South Africa’s 23 MPAs for alien species and applied Classification and Regression Tree Analysis (CART) to identify drivers of invasions in these protected areas. Non-indigenous species were recorded in all except two MPAs i.e. Sixteen Mile Beach and Helderberg MPAs, the only two MPAs to support only sandy beach habitat. Langebaan Lagoon was the most invaded MPA supporting nine alien species, followed by Betty’s Bay and Amathole MPAs which supported seven species each. The invasive Mediterranean mussel, Mytilus galloprovincialis, was the most widespread alien species, occurring in 68% of MPAs visited. It was most prominent on the island MPAs of the West Coast National Parks. The bryozoan, Bugula dentata, was also widespread, occurring across all three ecoregions. This study documented the hydrozoans Obelia dichotoma and Obelia geniculata, the bryozoan Cryptosula pallasiana and the ascidians Microcosmus squamgiger and Diplosoma listerianum outside of harbours for the first time, highlighting the need for monitoring of natural habitats. CART analysis identified the presence of large harbours in the vicinity of MPAs and the close proximity of yacht marinas as important predictors of invasions. This highlights the need for consideration of marine invasions during spatial planning of MPA networks, if these protected areas are to achieve their conservation goals.